I am not surprised by anything the photo department "experts" know. I once bought 100 speed color print film and the clerk told me that it is suitable only for portraits and other static subjects and that I should buy 400 speed instead. I didn't think to tell him that all of those National Geographic color pictures of the 1940's and 50's were taken with either ASA 10 Kodachrome or ASA 32 Ektachrome E-1.